This invention relates to stabilized DC power supply devices and, in particular, such devices for providing a plurality of DC power outputs which are selectively consumed.
As a system for regulating a voltage level of a DC power output, a switching type regulating system has been known wherein a switching element is provided with between a DC power source and a DC power output. The on-off operation of the switching element is controlled in response to the variation of the DC output voltage level. In this system the electric power is controlled by the switching element to stabilize the DC output voltage level. This system is known as a system that a power loss is little.
In case a plurality of stabilized DC powers are required, a plurality of switching type regulating systems are provided. But, if a plurality of stabilized DC powers are selectively used or consumed, it is not economical to use a plurality of switching type regulating systems.
Positive and negative DC powers are required for an audio-signal power amplifier of a complementary output type and they are selectively consumed at the amplifier. When one of the DC powers is consumed, the other is not loaded. It is not economical and makes the power supply device larger and weighter to provide a voltage regulating system to a non-loaded power.